They tamed the photon: early days of radiation dosimetry.

This article is a tribute to the many physicists who tamed the photon in the service of mankind. Many received Nobel Prizes and other high awards. Several have units named after them. Some invented the equipment we use. Some sacrificed their lives before the hazards and benefits of radiation were fully understood. I discuss the progress over 120 years, both theoretical and technical, in the development of radiation protection regulations based on quantitative measurements and a consistent set of units, the gray and sievert. It is an expanded version of a recent talk I gave at the ISHRAD (International Society for the History of Radiology) meeting in Würzburg which commemorated the 120th anniversary of the discovery of X-rays by Wilhelm Conrad Rontgen.

Immunosuppression in cervical cancer with special reference to arginase activity.

INTRODUCTION: Cervical cancer is characterized by an immunosuppressive microenvironment and a Th2-type cytokine profile. Expression of arginase (ASE), the enzyme that converts L-arginine into L-ornithine and urea, is stimulated by Th2-type cytokines. OBJECTIVE: To assess the association of ASE activity and L-Arg metabolism products with cervical cancer. METHODS: Sera of 87 and 41 women with histologically confirmed by colposcopy-directed biopsy SCC and CIN3 respectively and 79 with normal cytology or Low-Grade Squamous Intraepithelial Lesion (LSIL), were evaluated. Cytokines were measured using Milliplex Human cytokine/chemokine kit. Arginase (ASE) activity was determined using an enzymatic assay. Levels of L-arginine, L-ornithine, putrescine and spermine were determined by HPLC. RESULTS: Significantly higher levels of ASE activity were observed in women with CIN3 (age-adjusted OR: 24.3; 95%CI: 3.82-155) and SCC (AOR: 9.8; 95%CI: 2.34-40.8). As expected, possibly due to high levels of ASE activity, higher levels of l-Arg were negatively associated with CIN3 (AOR: 0.03; 95%CI: 0.004-0.19) and SSC (AOR: 0.06; 95%CI: 0.02-0.24). Consistent with the role of ASE in the conversion of L-arginine to L-ornithine and polyamine production therefrom, women with cervical cancer had higher levels of spermine and putrescine. A correlation analysis revealed a significant albeit weak relationship between high levels of IL-10 and high levels of ASE (Pearson r=0.32, p-value=0.003) in women with cervical cancer. CONCLUSION: This study indicates that ASE activity and L-Arg degradation mechanisms of immunosuppression are present in cervical cancer. The results foster research in the design of possible strategies to inhibit ASE activity for therapy of cervical cancer.

Interferon-gamma-induced nitric oxide inhibits the proliferation of murine renal cell carcinoma cells.

Renal cell carcinoma (RCC) remains one of the most resistant tumors to systemic chemotherapy, radiotherapy, and immunotherapy. Despite great progress in understanding the basic biology of RCC, the rate of responses in animal models and clinical trials using interferons (IFNs) has not improved significantly. It is likely that the lack of responses can be due to the tumor's ability to develop tumor escape strategies. Currently, the use of targeted therapies has improved the clinical outcomes of patients with RCC and is associated with an increase of Th1-cytokine responses (IFNγ), indicating the importance of IFNγ in inhibiting tumor proliferation. Thus, the present study was designed to investigate a new mechanism by which IFNγ mediates direct anti-proliferative effects against murine renal cell carcinoma cell lines. When cultured RCC cell lines were exposed to murine recombinant IFNγ, a dose dependent growth inhibition in CL-2 and CL-19 cells was observed; this effect was not observed in Renca cells. Growth inhibition in CL-2 and CL-19 cell lines was associated with the intracellular induction of nitric oxide synthase (iNOS) protein, resulting in a sustained elevation of nitric oxide (NO) and citrulline, and a decrease in arginase activity. The inhibition of cell proliferation appears to be due to an arrest in the cell cycle. The results indicate that in certain RCC cell lines, IFNγ modulates L-arginine metabolism by shifting from arginase to iNOS activity, thereby developing a potent inhibitory mechanism to encumber tumor cell proliferation and survival. Elucidating the cellular events triggered by IFNγ in murine RCC cell lines will permit anti-tumor effects to be exploited in the development of new combination therapies that interfere with L-arginine metabolism to effectively combat RCC in patients.

Effect of arginase II on L-arginine depletion and cell growth in murine cell lines of renal cell carcinoma.

BACKGROUND: L-arginine is the common substrate for the two isoforms of arginase. Arginase I, highly expressed in the liver and arginase II mainly expressed in the kidney. Arginase I-producing myeloid derived suppressor cells have been shown to inhibit T-cell function by the depletion of L-arginine. On the other hand, arginase II has been detected in patients with cancer and is thought to metabolize L-arginine to L-ornithine needed to sustain rapid tumor growth; however its role in L-arginine depletion is unclear. Thus, in tumor biology, L-arginine metabolism may play a dual role in tumor growth and in the induction of T cell dysfunction. Therefore, we studied in murine renal cell carcinoma (RCC) cell lines, the effect of arginase II on tumor cell proliferation and L-arginine depletion. The effect of arginase inhibitors on cell proliferation was also tested. METHODS: Three murine renal cell carcinoma (mRCC) cell lines were tested for the presence of arginase. nor-NOHA, an arginase inhibitor was used to substantiate the effect of arginase on cell growth and L-arginine depletion. Amino acid levels were tested by HPLC. RESULTS: Our results show that mRCC cell lines express only arginase II and were able to deplete L-arginine from the medium. Cell growth was independent of the amount of arginase activity expressed by the cells. nor-NOHA significantly (P = 0.01) reduced arginase II activity and suppressed cell growth in cells exhibiting high arginase activity.The depletion of L-arginine by mRCC induced the decrease expression of CD3zeta a key element for T-cell function. CONCLUSION: The results of this study show for the first time that arginase II produced by RCC cell lines depletes L-arginine resulting in decreased expression of CD3zeta. These results indicate that RCC cell lines expressing arginase II can modulate the L-arginine metabolic pathway to regulate both cell growth and T-cell function. Blocking arginase may lead to a decrease in RCC cell growth and aid in restoring immune function by increasing L-arginine availability for T-cell use. Understanding the interplay between arginase II and its interaction with the immune system may provide future therapeutic benefits to treat patients with RCC.

Determination of beta-agonists in liver and retina by liquid chromatography-tandem mass spectrometry.

A liquid chromatography-tandem mass spectrometry (LC/MS/MS) method for the determination of bromobuterol, cimaterol, clenbuterol, clenpenterol, hydroxymethylclenbuterol, isoxsuprine, mabuterol, ractopamine, ritrodrine, salbutamol, terbutaline, and tulobuterol residues in bovine liver and retina is reported. This procedure uses enzymatic digestion, liquid-liquid extraction, and cleanup on Oasis HLB solid-phase extraction cartridges, followed by determination of the residues by LC-tandem quadrupole MS using atmospheric pressure chemical ionization in the positive ion mode. Overall average recoveries ranged from 23 to 76% for liver and 34 to 77% for retina. The mean values for samples fortified at levels between 0.5-2.0 microg/kg (liver) and 5-20 microg/kg (retina) agreed within 98-118% of the spiked levels, with coefficients of variation ranging from 6 to 20%. The decision limits, CCalpha, ranged from 0.1 to 0.3 microg/kg for liver, 1-3 microg/kg for retina, and detection capabilities, CCbeta, from 0.2-0.5 microg/kg for liver and 2-5 microg/kg for retina.